How do I create Shopify theme extension app that displays inventory levels

[Laderlappen]

Good day!

I want to add the ability to my app to display the stock levels of a product on the store page.

The only methods I see to do this is with App Blocks or App Embeds. 
But app blocks are only supported in V2.0 stores and App Embeds only display at the top (head) or bottom (body) of the page or they have to be set to absolute locations. 
Is there a way to put this inventory counter in the page next to the product so that it will also work in V1.0 shops too?